TABLE 4.

Log EC₅₀ values and % maximum response to isoprenaline for CRE-SPAP production for the agonists cimaterol and CGP12177 at the human β₂-WT and chimeric β₂/β₁-receptors, where mutations in the β₂-WT mean that each TM region in turn is mutated to that of the β₁-WT (see Table 1)

Log K_B values for several antagonists for inhibition of the cimaterol and CGP12177 responses are also given. These data were obtained from stable cell lines; n refers to the number of separate experiments. Although there are some differences among the mutant receptors (e.g., β₂-TM2 has higher affinity for CGP20712A than β₂-WT), there is no highly significant consistent change in one mutant receptor compared with the others.

	Cimaterol Log EC50	% Isoprenaline	n	Log KB CGP20712A	n	Log KB Bisoprolol	n	Log KB ICI118551	n	Log KB Propranolol	n	Log KB CGP12177	n
Cimaterol as agonist: β2 stable cell lines
β2-WT	−9.05 ± 0.08	101.5 ± 3.2	13	−6.03 ± 0.12	8	−6.85 ± 0.10	8	−9.56 ± 0.07	8	−9.65 ± 0.05	14	−10.00 ± 0.05	9
β2-TM1	−9.45 ± 0.06	105.3 ± 2.8	9	−6.46 ± 0.10	8	−6.82 ± 0.09	10	−9.74 ± 0.08	9	−9.56 ± 0.06	19	−9.74 ± 0.11	19
β2-TM2	−9.64 ± 0.08*	102.1 ± 1.8	12	−7.20 ± 0.11*	8	−7.25 ± 0.10	7	−9.30 ± 0.11	8	−9.87 ± 0.03	14	−10.01 ± 0.06	9
β2-TM3	−9.21 ± 0.13	98.3 ± 4.1	7	−6.57 ± 0.12	7	−7.05 ± 0.13	6	−9.71 ± 0.10	7	−9.81 ± 0.07	11	−10.00 ± 0.10	10
β2-TM4	−9.66 ± 0.06*	103.3 ± 2.4	13	−6.09 ± 0.09	10	−6.75 ± 0.03	9	−8.87 ± 0.04*	10	−9.34 ± 0.06	14	−9.83 ± 0.05	9
β2-TM5	−8.97 ± 0.09	100.6 ± 2.4	13	−6.63 ± 0.12	10	−7.04 ± 0.09	9	−9.50 ± 0.09	9	−9.46 ± 0.04	13	−9.82 ± 0.07	4
β2-TM6	−8.74 ± 0.05	101.0 ± 4.7	12	−7.05 ± 0.15*	7	−7.07 ± 0.10	9	−8.86 ± 0.12*	9	−9.52 ± 0.06	11	−9.59 ± 0.13	8
β2-TM7	−8.77 ± 0.06	107.4 ± 2.9	10	−6.54 ± 0.04	14	−7.06 ± 0.09	11	−9.18 ± 0.07	12	−9.30 ± 0.06*	17	−9.72 ± 0.10	13
	CGP12177 Log EC50	% Isoprenaline	n	Log KB CGP20712A	n	Log KB Bisoprolol	n	Log KB ICI118551	n	Log KB Propranolol	n
CGP12177 as agonist: β2 stable cell lines
β2-WT	−9.35 ± 0.09	23.5 ± 3.9	14	−6.12 ± 0.09	3	−6.60 ± 0.14	11	−9.31 ± 0.17	11	−9.02 ± 0.12	19
β2-TM1	−9.48 ± 0.19	26.9 ± 1.7	9	−6.00 ± 0.16	9	−6.63 ± 0.12	12	−9.51 ± 0.17	12	−9.07 ± 0.08	20
β2-TM2	−9.20 ± 0.09	12.6 ± 1.9	11	−6.79 ± 0.11	8	−7.00 ± 0.09	9	−9.03 ± 0.11	10	−9.32 ± 0.10	14
β2-TM3	−9.19 ± 0.10	35.9 ± 3.3	9	−6.21 ± 0.29	4	−6.53 ± 0.12	8	−9.47 ± 0.16	8	−8.95 ± 0.09	21
β2-TM4	−9.20 ± 0.07	38.5 ± 2.4*	13	−6.05 ± 0.12	8	−6.34 ± 0.09	7	−8.42 ± 0.08*	11	−8.34 ± 0.08*	18
β2-TM5	−9.31 ± 0.07	28.8 ± 2.0	12	−6.47 ± 0.15	8	−6.98 ± 0.22	8	−9.31 ± 0.08	9	−8.75 ± 0.10	19
β2-TM6	−8.81 ± 0.10	22.4 ± 1.6	8	−7.31 ± 0.34	5	−6.74 ± 0.11	5	−8.39 ± 0.27	4	−9.11 ± 0.11	4
β2-TM7	−9.71 ± 0.12	41.3 ± 2.7*	9	−6.19 ± 0.15	10	−6.59 ± 0.16	10	−9.09 ± 0.14	9	−9.02 ± 0.08	22

^*P < 0.001 One-way ANOVA with post hoc Newman–Keuls comparing values from the mutant receptors with those obtained from the β₂-WT. Thus, the log K_B value for CGP20712A at β₂-TM2 obtained in the presence of cimaterol is different (P < 0.001) from that obtained in the β₂-WT receptor. In contrast to data on the β₁-receptor in Table 2, there are no values with P < 0.001 for one-way analysis of variance with post hoc Newman–Keuls comparing each value with all other values in this set.